This application proposes a three-year research program for the International Research Scientist Development Award (IRSDA) with a focus on the use of economic incentives to prevent sexually transmitted infections (STIs), at the University of California, Berkeley and the Mexican National Institute of Public Health (INSP). The candidate, Omar Galarraga, will have an appointment at the Institute for Business and Economic Research at UC Berkeley. He previously received a Ph.D. in Health Policy at Johns Hopkins University. The IRSDA will allow the candidate to have a period of mentored research to prepare him to Dursue an independent research career in international public health. The candidate's long-term goal is to contribute to human development by designing, implementing, and evaluating public health programs, particularly those related to sexually transmitted infections including HIV, using economic tools. He aims to develop a base of skills and knowledge critical in behavioral economic epidemiology. His specific aims are: 1) to study how economic factors affect sexual risk behavior in adolescents;2) to use advanced quantitative methods to measure behavior change;3) to gain experience in field research methods;and 4) to apply this knowledge of epidemiology, econometrics, and behavioral science and use it in a cost effectiveness analysis to inform future prevention programs. He plans to achieve these goals through a combination of direct coursework, one-on-one tutorials, mentored research projects, conference presentations, preparation of manuscripts for publication, and development of research proposals (R03, R01 or other) to become an independent researcher at the end of the award period. The evidence shows that traditional prevention methods have not been entirely successful for STI and particularly HIV prevention. Economic incentives for young persons who remain free of STIs are proposed as an example of a structural intervention that affects not only proximal but also distal and environmental risks. Dr. Galarraga will conduct preliminary work essential to test whether conditional cash transfers are effective in changing sexual risk behavior of adolescents and young adults in Mexico. More effective STI and HIV prevention programs are urgently needed, particularly in middle and low-income countries.